On 08/31/2010 05:34 AM, Gary Birkett wrote:
James,
A question about the patch for capacitive
" cy8ctmg110: Added fuzz to ABS_X and ABS_Y to remove jitter"
I cannot determine from the patch what it does, does it reduce the
resolution down to 4 unit blocks, or does it still allow single unit
sensitivity whilst removing jitters from around it?
You can see drivers/input/input.c input_defuzz_abs_event() for
implementation details on how fuzz is used internally within the input
system.
The result is that jitter around a stable point is reduced; the device
still retains the same total sensitivity, but once a contact point is
made, the data has a tendency to stick to that value until the threshold
is crossed.
If it it indeed the resolution limiting, perhaps something I did in
the past to remove jitter from the very noisy accelerometer might be
another alternative.
At each new reading from the sensor, I would move the "cursor" a
percentage fraction closer to that point rather than directly using it.
A kalman filter (or similar predictive algorithm) is also a great way to
remove noise from an accelerometer, without introducing latency into the
sensor read path.
James
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